Trucking system



Nov. 9, 1926. 1,606,006

W. C. WEAVER TRUNKING SYSTEM Filed May 22. 1924 2 Sheets-Sheet l fit Patented Nov. 9, 1926.

tlitlTED STATES tenant. f PATENT entice.

WIL'LTAM C. WEAVER,1OF EAST OEANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELEC- [ERIC OGMPAIQY, INCORPORATED, 01 NEW YORK, N. Y., A CORPORATION CF NEW YORK.

TRUNKING SYSTEM.

Application filed fiay ,22,

This invention relates to telephone trunking systems, and more particularly, to systems wherein a plurality of link or trunk lines are required.

The object of this invention is to provide an improved trunking system having as its outstanding characteristic great flexibility of trunk selection.

In accordance with this invention a number of trunks are divided into groups, each group accessible to a trunk finder switch adapted to huntthereover and to seize the first idle trunk in the group. A steering or pilot switch is likewise provided which has access to each of the trunk finder switches and is adapted to pilot or steer a calling line to one of the trunk finder switches in the group whereby an idletrunkisselected, the steering switch being controlled in turn by the trunlrfinder switch so that in case all for answering the calling lineand the jack end of a. trunk outgoing to a distant mechanical central ofiice. r

Fig. 2 shows thetrunk finder and steering switches and the operators control equipment.

When the receiver is removed at the substation 1, Fig. 1, the linerelay 7 operates and lights the line lamp 9. The call is answered by inserting the plug 32 in the jack 2, operating the relays S and 11 and extinguishing the line lamp 9. The listening key 33 is operated and the office code and line number of the desired line are obtained. The oflice key 17 peculiar to the desiredoffice is depressed, closing an obvious circuit to operate the relay 18. Relay 18 operated locks by Way of 19, 31, 235, and'i258 to ground. It also closes acircuit to operate relay 206 as follows: battery, winding of re lay 206, 30, 20 to ground. The steering switch has nonormal position anditremains in the position in which it is last us'ed. Brush 251 shown on Fig. 2 is resting onthe terminals associated with the lower one of 1924. Serial'No. 714,999.

the two trunk finders disclosed. Therefore, when relay 206 operates it, looks by way of 235 and 258 to ground, and closes a circuit to operate the stepping magnet 205 as follows: battery, winding of the stepping magnet205, 215, 251 216, 217, 218, 219, 252, 226, 213, 229 to ground. Stepping magnet 205 opens at 215 its own operating circuit and releases, advancing the brushes 210 to 21 1, inclusive, one step in an anti-clockwise direction, so that thebru'shes ar'enow posi= tioned upon the first terminal of each oithe' arcs 200a) 204,.inc1asive. The terminals or the y'arious arcs 200 to 20 1 are associated with a particular group o't-trunks and we will assume that each trunk in this group is busy, in whichcase, ground will be coanected to each terminal in the arc 2G3 and a circuit will be closed as followsto operate stepping magnet 205 battery, winding of the stepping magnet205, 215, 216, 21'1", 218, 219, 252, 226,213and 227 to ground. The brushes 210'to214, inclusive, will be adv'ancedto the terminals associated with the next trunk in the group and as all of the trunks" are busy, the cycle of operations will be repeated and the brushes will advance until the tweiity-fir'st terminal in each arc is reached. This will be the only time when one (if these switches will be normal as the brushes enames the terminals to which they were advanced at the time ofthe last call. Intliis position a circuit will be closed to operate the stepping magnet 205 as follows battery, winding of the stepping magnet 205, brush 250, 209, 236, 210, 2st, to ground. Th'e'stepping magnet 205operated closes a circuit'to operate the stepping niagnet 24l otthe steering switch as follows: battery, winding of the stepping magnet 24,4, 25s,. 238, 259, 245, 236, 210, 237 to ground. The stepping magnet24e operated opens its own operating circuit and releases, advancing the brushes 250 'to 253, inclusive, one step in an anti-clockwise direction. the brush 250 advances, the circuit previously traced for retaining the stepping rnag-- net 205 operated is opened, releasing this stepping magnet and advancing the brushes v210 to 214, -incl-usive,another step, in which position brushes 210, 211, 212 and 21 1 are opened, only brush 213 remaining in contact with the terminal 229. circuit .is now closed-to operate the stepping magnet 225 of thetrunk finder which has access to the next roup of trunks leading to the same oliice as rollowsz battery, winding of the stepping magnet 225, 246, 247, 251, 216, 217, 218, 219, 252, 248, 233, 249 to ground. Stepping magnet 225, in operating, opens at 246 its own operating circuit and releases, advancing the brushes 230 to 234, inclusive, one step in an anti-cloclrwise direction, and positioning them upon the first terminal of the arcs 220 to 224, respectively.

Let assume that all the trunks in this group except. the one represented by the leads 26, 27, 28 and 29 are busy, in which case, all the terminals oi the are 233 except terminal 254 will be grounded, and the circuit to operate stepping magnet 225 (previously traced) will be again closed and the brushes will be advanced and positioned upon the second terminal of each of the arcs 220 to 224, inclusive. This cycle of operations will continue until brush 233 is positioned upon the terminal 254. Since this trunk is idle, the lead 28 will be free from ground, hence, the stepping magnet 225 Wlll not reoperate. A circuit is now closedto operate relay 207 as follows: battery, winding of the stepping magnet 225, 246, 251, 216, 217, winding oi relay 207, 255 to ground. The stepping magnet 225 will not operate over the circuit traced due to the highre sistance of the winding of relay 207 in series with it. It should be observed that so long as the trunk finder switches were hunting for an idle trunk the relay 207 was prevented trom operating in series with the stepping magnet 205 or 225 due to the solid ground connected to either the brush 213 or the brush 233. Relay 207 operated connects solid ground to the lead 219, thence by way of brushes 252 and 233 to the terminal 254 of the trunk circuit, causing this trunk to testbusy to all other trunk finder switches.

The trunk circuit having been found the operators control equipment 256 is set in a manner (not shown) to indicate the number of the selected trunk to the operator. i As the trunk number indicating device forms no part of this invention, it is not described herein. A complete explanation of the operation of a suitable trunk number indicating device is given in the United States Patent to Clark 1,456,537, issued May 29, 1923.

The operators control equipment may also when necessary include a register sender such for example as the one shown in Figs. 9, 10, and 11 of the patent of Allen, No. 1,513,362, October 28, 1924.

When the operators control equipment has performed its necessary functions, the plug 4 will be inserted in jack 5 operating relay 14 over an obvious circuit, closing a circuit to operate relays 6 and 208 as follows: battery, right windin of relay 6, 34, 29, brush 234, 257, through the control equipment 256 (in a manner not shown), winding of relay 208, 237 to ground. Relay 208 operating opens at 258 the locking circuit for relay 206 which releases, in turn, releasing relay 207. The release of relay 207 opens the circuit through relay 208 which releases and the operators control equipment is re stored to normal.

When relay 6 operated over the circuit previously traced, it looked through its windings in series by way of 35 and 16 to ground. Relay 6 operated extends the out going trunk circuit to equipment at the distant mechanical otfice DMD.

If the operators control equipment Fig. 2 includes the register sender, the switches 23 and 24 at the distant mechanical oilice DMO have already been set over leads 26 and 27 in a manner not shown, but which is fully described in the patent of Allen, supra. 1f the operators control equipment does not include a register sender the switches 23 and may be set by means of a dial (not shown) connected to the cord circuit Fig. 1.

In any event, the called station 25 is signalled and answers and the talking connection is established. When the receiver is replaced upon the switchhook at the calling station 1, relay 11 releases and the supervi sory lamp 10 is lighted as a disconnect signal. When the receiver is replaced on the switchhook at the called station 25, relay 12 releases and the lamp 13 lights as a disconnect signal. When the plugs 32 and 4 are removed trom the jacks 2 and 5, respectively, relays 8, 14 and 6 release, and the circuit is restored to normal. 1

While for purposes of illustration the invention has been disclosed in connection with a telephone system between a manual and a mechanical central office, it is not so limited, but may be used as a trunk finder in any signaling system wherein the use 01"" a large number of trunks or link circuits necessitates the division of such trunks or links into a number of equivalentgroups.

Vfhat is claimed is:

1. In a trunking system, a plurality of trunks arranged in groups, a plurality of trunk selectors, there being as many trunk selectors as there are trunk groups, each selector having access to any idle trunk in its particular trunk group, operating circuits for said selectors, a steering switch for successively establishing the operating cir cuits of said selectors therethrough to render the selectors operable, and means controlled by each trunk selector for ad vancing the steering switch so as to associate it with the next selector. 7

2. In a telephone system, a line, a pin rality of trunk lines arranged in two or more groups, a hunting device associated with the first group, said device adapted to move over the lines in its group and to seize the first idle line therein, a second hunting device similarly associated with respect to the second group, a steering switch adapted to establish the operating circuits of said hunting devices in succession therethrough, and means included in the first hunting device eiiective when all lines accessible thereto are busy for advancing the steering switch to render the second hunting device operable.

3. In a telephone system, a line, a plurality of other lines arranged in groups, a hunting device associated with the first group, said device adapted to move over the lines in its group and to seize the first idle line therein, a second hunting device similarly associated with respect to the second group, a third hunting device similarly as sociated with respect to the third group etc., a steering switch adapted to establish the operating circuits of said hunting devices in succession therethrough, and means included in each hunting device effective when .all lines accessible thereto are busy for advancing the steering switch to render the next hunting device operable.

t. In a telephone system, a pilot switch, a plurality of hunting devices to the operating circuits of which said pilot switch has access in succession, a plurality of groups of lines, there being one group of lines per operating circuit of the next succeeding hunting device and the cycle of operations is repeated.

In witness whereof, I hereunto subscribe my name this 19th day of May A. D. 1924;.

WILLIAM G. WEAVER. 

